@tokens = ...;
$tokens = join '', map { $tokenToChar{ $_->type } }, @tokens;

if ($tokens =~ / ($IDENT)($DOT $IDENT)* /x) {
     my @captured = map { [ @tokens[ $-[$_], $+[$_] ] } 1..$#-;
     my ($head, $tail) = @catpured;
}